The year is divided into 365 standard days, which are grouped into 52 weeks of seven days each The lengths of days and weeks is a legacy of Terran domination during the second Imperium. Days are numbered consecutively, beginning with one. The first day of the year is a holiday and is not part of any week. For example, the first day (Holiday) of the year 1116 is 001-1116. The last day of the year is 365-1116.
Days of the week are :
Source : http://wiki.travellerrpg.com/Imperial_calendar